Inductive winding

ABSTRACT

A tubular aluminum member is extruded in a rectangular shape and cut to a given length. The four walls of the tubular member are successively cut by a circular saw to form a portion of the tubular member into a generally spiral shape winding with terminal portions at each end. The member is treated to form an insulating layer on the surfaces of the member including the facing sides of the winding to form an inductive winding for passing current. The winding may be compressed and one set of edges treated for engagement by current taps to produce a variable voltage and current device.

United States Patent [191 Davis 1 1 3,731,243 1451 May 1,1973

. [76] Inventor:

[ INDUCTIVE WINDING Ariel R. Davis, 3476 Fleetwood Drive, Salt LakeCity, Utah 84109 [56] References Cited UNITED STATES PATENTS 999,7498/1911 Chubb ..336/223 X 1,308,448 7/1919 Sandell ..336/223 X 1,738,52812/1929 Dunlop ..336/223 X 2,061,388 11/1936 Schou ..336/223 X 2,385,98310/1945 Hanes ..336/223 X 2,896,179 7 1959 Laurie ..336/223 x 3,025,4523/1962 Ross ...336 229 X 3,142,809 7 1964 Remenyik ..336/61 3,150,339 91964 Wilska 336/223 x 3,188,589 6/1965 Snowdon. 336/148 x 3,466,7439/1969 DoPuy "336/61 X Primary Examiner-Thomas J. Kozma Attorney-GeorgeC. Bower [57] ABSTRACT A tubular aluminum member is extruded in arectangular shape and cut to a given length. The four walls of thetubular member are successively cut by a circular saw to form a portionof the tubular member into a generally spiral shape winding withterminal portions at each end. The member is treated to form aninsulating layer on the surfaces of the member including the facingsides of the winding to form an inductive winding for passing current.The winding may be compressed and one set of edges treated forengagement by current taps to produce a variable voltage and currentdevice.

19 Claims, 20 Drawing Figures PAIENTEDHAY 1 m5 3.731.243

SHEET 1 [IF 5 INVENTOR.

W 5% Anne/v5 PATENTEDMY' 1 ma SHEET 2 OF 5 INVENTOR, 49/54 ans 55 6WAnne/v0 PATENTED 11973 3.731.243

SHEET 3 OF 5 INVENTOR.

jayzfgm INDUCTIVE WINDING RELATED APPLICATIONS This application is acontinuation of US. Pat. application Ser. No. 99132, filed on Dec. 1 l,1970 and entitled An Inductive Winding and Method of Manufacture," nowabandoned.

BACKGROUND OF THE INVENTION The usual method of forming inductivewindings is to wrap cylindrical copper wire around a core. Inductivewindings have also been formed by interleaving sheet metal strips withinsulating pieces to form an inductive winding or bending continuousmetal ribbon into inductive turns. The standard cylindrical wire type ofwinding has problems of heat dissipation through the layers of turns andcorrosion and pitting of the wire on engagement by a variable voltagetap. The stacked laminations of sheet metal and insulating piecesrequires the transfer of current between engaging surfaces of thelaminations. The distortion of an edge bent metal ribbon to form aninductive winding is not satisfactory. All of the foregoing forms havean additional disadvantage of transference of load current acrossconnections. Such connections are a source of maintenance problems.

SUMMARY OF THE INVENTION An inductive winding is formed from a tubularmember by cutting around the wall of the tubular member to formcontinuous turns of a winding with terminal portions at each end so thatcurrent is passed from the terminal portions through the windingswithout transferring between two engaging surfaces.

An object of the invention is to provide a single piece inductivewinding that has fiat side surfaces between and on the turns.

Another object of the invention is to provide an inductive winding withterminal portions that are formed with the inductive winding as a singlepiece.

Another object of the invention is to provide an inductive winding thatpasses current without transfer between surfaces and conducts heatthrough the side surfaces of the winding.

Another object of the invention is to provide an inductive winding and aheat sink as a single piece of metal.

Another object of the invention is to provide as a single piece aninductive winding and a component supporting member in electricalconductive relation with the winding and support member.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I perspectively illustrates anuncut tubular member with exterior smooth surfaces.

FIG. 2 perspectively illustrates an uncut tubular member with exteriorfins on three surfaces.

FIG. 3 perspectively illustrates the exterior smooth surface tubularmember with winding cut therein.

FIG. 4 perspectively illustrates a finned tubular member with the finsremoved from a section and a winding formed therein.

FIG. 5 perspectively illustrates a finned tubular member with thewinding section having fins.

FIG. 6 illustrates the smooth side of the finned tubular member withnotches for passing an iron core member.

FIG. 7 is a view of one of the sides illustrating cuts forming thewinding.

FIG. 8 illustrates a surface adjacent to the surface shown in FIG. 7.

FIG. 9 illustrates the turns of the winding spaced.

FIG. 10 is a fragmentary perspective view of the turns of the winding.

FIGS. 11 and 12 illustrate the cutting of the wall of the tubular memberby a circular saw.

FIG. 13 fragmentarily illustrates a toroidal winding.

FIGS. 14a through d diagrammatically illustrate the fragments of thesides of the uncompressed toroidal winding.

FIG. 15 is a diagrammatic view illustrating the relationship of thetubular member and the circular saw.

FIG. 16 is a fragmentary sectional view of a winding with a plurality ofvariable contacts.

FIG. 17 illustrates a transformer with a winding in accordance with theinvention.

DETAILED DESCRIPTION Referring to FIG. 1 of the drawings, a tubularmember 20 is illustrated having a bore 21 extending longitudinallytherethrough and of a generally square configuration formed by walls 22,23, 24, 25. The tubu lar member may be made of aluminum and extrudedthrough a die with a floating mandrel using a hollow aluminum billet.The aluminum may be 6063 or EC grade with a T6 temper for best machiningqualities. The tubular member is cut in any desired length from theextrusion. The exterior surfaces of the walls may be smooth or, asillustrated in FIG. 2, have cooling fins 26, 27, 28 extendinglongitudinal to the member and perpendicular to the walls 22, 23, 25.The exterior surface of wall 24 is smooth. The walls of the tubularmember are cut as described later herein to form a winding 35 withterminal portions 36, 37 at each end as illustrated in FIG. 3.

The fins may be removed (FIG. 4) from a portion of the member to form awinding section 30 with flat sides 22 to 25 and a heat sink section 31with cooling fins 26, 27, 28. The winding section 30 with the flat sidesmay be cut in accordance with the method of this invention to form aninductive winding 32 while the heat sink section 31 supports electricalcomponents (not shown). In the embodiment of FIG. 5 the winding 38 iscut in the finned embodiment of FIG. 2 without removing the fins fromthe winding section, so that the winding 38 has fins 26, 27, 28.

The tubular member 20 or winding section 30' has longitudinal cuts 40,41 in the smooth exterior wall 24 (FIG. 7) immediately adjacent to theopposite walls for forming notches 50, 51 in the side for subsequentlyreceiving an iron core. A longitudinally extending bore 42 may be cut inone of the walls for receiving a terminal prong 39 threaded therein.

The winding or coil 35 is cut in the tubular member 20 by fitting thetubular member in a vise or clamping rotating saw 45 downwardly throughthe upper side 22 of the tubular member. The circular saw 45 (FIGS. 11,12) is perpendicular to the side 22 to be cut and centered in relationto the sides 23 and 25. The axis A (FIG. of the saw is at a slight angleto plane B extending longitudinally midway between the sides 23, 25 andperpendicular to the side 24. The center point of the saw is in thisplane B. The saw has a diameter so that the periphery of the saw cutseach of the inner and outer corners 46, 47, 48, 49 of a side at the sametime. This is best illustrated by the curved line 56 between corners 46,47 (FIG. 12). The member is then removed from the vise or clampingmembers and rotated 90 to present side 23 for cutting (FIG. 11). Theplane B extends longitudinally midway between the sides 22, 24 andperpendicular to side 25. The axis A of the saw is at a slight anglewith the centerpoint of the saw in the plane. The tubular member ispositioned so that on completion of the cut in this side the saw is inline with the portion of the previous cut 50 inside 22. The cut 50 iscontinuous through successive sides. Instead of a single sawbeing used,multiple saws may make all cuts in one wall of the tubular member at thesame time. Thus by four successive positions of the tubular member theentire winding can be formed. The first and last cuts on the wall 24intersect the longitudinal slots 40, 41 to form the slots 51, 52 for theiron core.

As seen from the fragmentary views of the winding in FIGS. 9 and 10 thesuccessive angular cuts in the walls 22, 23, 24 and 25 produce arectangular shaped winding with a continuous space 50 between the turns.The winding in this form is resilient and may be compressed so that theside surfaces 53 and 54 in the wall 22, side surfaces 55, 56 in the wall23, side surfaces 57, 58 in the wall 24 and side surfaces 59, 60 in thewall 25 are in engagement. A thin insulating coating, later describedherein, is provided on these sides to isolate the turns and form thewinding into an inductive winding. Thus the side surfaces may becompressed in a close contiguity for transfer of heat therebetween.

The tubular member with the winding 35 and the terminal portions 36, 37may be heat treated and annealed to a soft temper to increase theconductivity of the metal. The tubular member can then be furthertreated to form an insulating coating on the surface of the tubularmember and particularly the facing sides 53, 54 of the winding. Also,the facing sides 55, 56; 57, 58 and 59, 60 require an insulatingcoating. The fins are also treated. The coating also improves theradiation properties of the tubular member and various colors may beprovided depending upon the desired appearance. The anodized coating onthe side walls of the winding permits the winding to be pressed togetherwithout shorting the windings while permitting substantial heat flowbetween the surfaces to provide a short heat path for removal of theheat from the windings.

An insulating coating may also be provided by covering the tubularmember with an epoxy cement containing glass spheres of 0.004 inch to0.005 inch in diameter. The insulating glass spheres maintain a minimumspacing between the windings so that the side surfaces of the windingshave a layer of epoxy therebetween.

- The glass spheres act as spacers when the coils of the winding areforced together and prevent the extrusion of the-epoxy and a metal tometal contact between the windings. Thus an adequate insulating isprovided between the turns. I

Additional coating may be provided on the exterior surfaces of thetubular member and fins by spraying an epoxy on the surface or byheating the tubular member and placing it into a bed of epoxy powder.This may be done on an anodized tubular member and an unanodized tubularmember.

In the coating process masks may be applied to the metal surfaces atdesired areas where electrical contact with the metal is desired.

The winding may be held in a compressed condition by an insulating plate61 being positioned along one of the sides of the tubular member 20 orwinding sections 30 or winding 38 and fastened to the terminal portionsat each end. The insulating plate 61 has matching notches. The tubularmember with the winding may be used in various embodiments. For example,a primarywinding 62 (FIG. 17) may be positioned around the outside ofthe tubular member and an iron core 63 fitted in the bore. The iron coremay be made of U- shaped silicon steel straps or be made of a tape woundcore cut into U shapes or may be powdered iron or powdered ferritemoulded into U shapes. The U shapes each have a leg inserted into thebore 21. The ends of the bore may be closed by plates 66 and the borefilled with rubber, flexible urethane, flexible rubber, silicon rubberor the like and solidified by a catalyst or heating to support the ironcore and electrically isolate it from the winding. The elastomer assistsin absorbing noise that may be caused by vibrations of the iron core.The winding sections 30 and 38 also have an insulating plate 61 and aniron core 63.

The legs of the two U-shaped pieces 64, 65 may be in contact or may bespaced, depending upon the characteristics to be imparted to theassembled unit. A mica spacer 67 may be positioned between the ends ofthe legs. Cores with a small air gap may be used to provide linearreactors. The gap between the cores can be adjusted depending upon thelinearity of saturation of the core that is desired. This will dependupon the use of the device. The tubular member with the winding isparticularly useful where high load currents are passed by the winding.Such load currents occur in chokes used in series with solid statecontrolled devices, in rectifier power supplies, in adjustableautotransformers, dimmer and magnetic amplifiers, linear reactors andthe like.

For solid state controlled devices the tubular member with heat sink 31(FIG. 4) is used. The solid state controlled devices are mounted in theheat sinks. Thus the heavy currents passed by the solid state controlleddevices are conducting through the terminal portions, winding, into theheat sink with the current passing only through the surfaces betweensurfaces of the heat sink and solid state controlled devices. Thisgreatly reduces the factors that create heat and also provides a readydissipation of any heat created by the same element that is carrying theheat.

In FIG. 16 a fragmentary sectional view of an adjustable autotransformer70 having a plurality of variacurrents through bridged windings and acontact 71. The contact 71 may be made of any suitable material, such ascarbon.

The tubular member with the winding and terminal portions, including theembodiments with the heat sinks and fins, may be utilized in manydifferent types of apparatus of which the foregoing are onlyillustrative.

In FIGS. 13 and 14 a toroidal winding 35a is fragmentarily illustratedand embodies the principles of the invention. The tubular member a haswalls 22a to 250. The walls 22a and 24a are cut as shown in FIGS. 14band d. The walls 22a and 24a have pie or V-shaped cuts 22c and 240between the winding segments 22b and 24b, respectively, The cuts may bemade by positioning the axis of the saw shaft at an angle A on one sideof plane B and then at an angle A on the other side of plane B. The pieshaped cuts in the wall 24a are similarly formed with the narrowportions at the wall 23a. The wall 23a has the narrow segments 23b andthe wall a has the broad segments 25b formed by the cuts 23c and 25c atan angle C to the plane B. The winding compresses into a circularconfiguration as partially illustrated in FIG. 13. The tapered segments22b and 24b are normal to the sides 23a and 25a on cutting and as sume aradial position on compression, The general spiral configuration to forman inductive winding is attained by the slope of the segments 23b and25b. As illustrated in FIGS. 14a and 14b the angle C is greater thanangle A. The segments are arranged in FIGS. 14a and b with contactingends adjacent in the figures to illustrate the progression of thewinding. The surface of the winding may be treated as in the otherembodiments to provide an insulating coating by anodization orpolymerization of a resin. The surfaces 22a may be provided with asurface similar to the embodiment of FIG. 16 for engagement by movablecontact means to tap a range of voltages and currents.

It is thus seen from the foregoing description that a new type ofinductive winding and method of manufacture of an inductive winding havebeen provided. The winding may be formed by machinery and may beautomated. The tubular member is readily extruded and the winding cut toprecise dimensions rapidly by multiple circular saws. The insulatingsurfaces on the winding may be readily produced by standard anodyzingprocesses.

The winding has the particular feature that the winding and terminalportions are a single piece without any current transferring surfaces orconnections. Also, the individualturns are flat rectangular pieces withconsiderable depth normal to the exterior surfaces of the winding andwith extended transverse facing surfaces for the transference of heatlongitudinally along the winding. This is particularly advantageous whenvariable contacts engage the outer surfaces of the windings for tappingvarious voltages or currents therefrom. Heat produced between thecontact and the winding is carried inwardly and longitudinally fordissipation, thus reducing or preventing the pitting or corrosion of theengaging surfaces. Further, the winding may be readily provided withcooling fins and may be formed as a single piece with a heat sink fordissipation of heat developed in the winding. Further, the heat sink maybe used to support other heat generating electrical components whichwill be in electrical conductive relation with the winding by atransference of current through a single contacting surface. Thus theamount of heat generated is greatly reduced and the heat that isgenerated may be readily dissipated. Therefore, an inductive windingwith heat dissipating means may be readily manufactured by machinemethods which has good heat dissipating and current transferringcharacteristics.

Various modifications and changes may be made in the various embodimentswithout departing from the invention as set forth in the appendedclaims.

Iclaim:

1. An inductive winding formed by a continuous spiral-like cut in thefour walls of a rectangular tubular member comprising two longitudinallyspaced terminal portions, serially connected rectangularly shaped turnsbetween said terminals, each of said turns having four members withaxially and oppositely facing side surfaces generally normal to thelongitudinal axis of said tubular member and having offset corners tosuccessively connect and tilt said members in a generally spiralconfiguration around said longitudinal axis between said terminalportions as a single conductive piece.

2. An inductive winding as set forth in claim 1 wherein each of saidmembers have a substantially uniform cross sectional area between saidrespective corners.

3. An inductive winding as set forth in claim 2 wherein insulation meansis betweensaid turns.

4. An inductive winding as set forth in claim 1 wherein said tubularmember is aluminum and has an anodized insulating coating and means areprovided to hold said winding in compressed relation with adjacent turnsseparated by said insulating coating.

5. An inductive winding as set forth in claim 1 wherein cooling fins areprovided extending outwardly from said turns and formed as a singlepiece therewith.

6. An inductive winding as set forth in claim 3 wherein said turns ofsaid winding have cooling fins immediately part of said turns and normalto said outer surface and longitudinal to said winding.

7. A transformer comprising a wall having inner and outer surfacesforming a tubular-like member having a main longitudinal axis, a cutthrough said wall at a slight angle to a plane normal to the main axisto longitudinally space loops of said out to form said wall into acontinuous winding of a plurality of turns, said turns being formed ofsuccessive members and corners connecting successive members at rightangles and at a slight angle to the plane of the preceding member toinductively form said turns, said members having uniform cross sectionsbetween respective corners and having successive flat side surfaces oneach side facing respective successive flat side surfaces of an adjacentturn, insulating means between said side surfaces, said side surfacesand said insulating means therebetween being compressed to transmit heattherethrough and said insulating means electrically isolate said turnsso as to solely pass current serially through said turns, an iron coreextending through said winding and a second winding electricallyisolated from said first winding and in inductive relation therewith forforming a transformer relation.

Isive members at right angles to one another, said connecting cornershaving transversely offset portions positioning said successive membersat a slight angle to one another to inductively form said members andcorners into. inductive turns, said members having substantially planarside surfaces on opposite sides of a respective member in facingrelation with planar side surfaces of adjacent members with saidinsulating coating between respective facing surfaces.

9. An inductive winding as set forth in claim 1 wherein a ferromagneticcore is provided extending through said winding.

10. An inductive winding as set forth in claim 1 wherein there is anextension from one of said terminal portions for supporting currentcontrolled devices and dissipating heat.

11. An inductive winding as set forth in claim 10 wherein said extensionhas heat dissipating means extending therefrom.

l2. An inductive winding as set forth in claim 10 wherein saidextension, said terminal portions and said turns are a Single piece.

13. An inductive winding as setforth in claim 1' wherein said membershave a substantially greater depth than longitudinal thickness.

14. An inductivewinding as set forth in claim 13 wherein heatconductive, electrical insulating means and means for pressing saidturns together are provided for transmission of heat between the sidesurfaces while said turns serially pass current.

15. An inductive winding as set forth in claim 1 wherein said terminalportions have notches on the same side and at opposite ends of saidwinding and a closed ferromagnetic core is provided extending axiallythrough said winding.

16. An inductive winding as set forth in claim 1 wherein said turns haveouter members and inner members of less thickness than said outermembers and have pie-shaped members on opposite sides of said windingfor connecting opposite ends of said inner and outer members to form thewinding in a curved shape.

17. An inductive winding as set forth in claim 16 wherein aferromagnetic core is provided extending through said winding.

18. An inductive winding as set forth in claim 16 wherein insulatingmeans and means for pressing said side surfaces facing one anothertogether is provided for transmission of heat between said surfaces ofsaid turns while serially passing current therethrough.

19. An inductive winding as set forth in claim 1 wherein said turns havea heat conductive, electrically insulating means between said turns andmeans are provided for pressing said turns together with said sidesurfaces in facing relation passing heat therebetween while passingcurrent serially therethrough and an extension is provided on one ofsaid terminal portions for carrying current devices controlling thecurrent through said winding, and said extension being m heat transferrelation with said device and said winding for dissipation of heat.

1. An inductive winding formed by a continuous spiral-like cut in thefour walls of a rectangular tubular member comprising two longitudinallyspaced terminal portions, serially connected rectangularly shaped turnsbetween said terminals, each of said turns having four members withaxially and oppositely facing side surfaces generally normal to thelongitudinal axis of said tubular member and having offset corners tosuccessively connect and tilt said members in a generally spiralconfiguration around said longitudinal axis between said terminalportions as a single conductive piece.
 2. An inductive winding as setforth in claim 1 wherein each of said members have a substantiallyuniform cross sectional area between said respective corners.
 3. Aninductive winding as set forth in claim 2 wherein insulation means isbetween said turns.
 4. An inductive winding as set forth in claim 1wherein said tubular member is aluminum and has an anodized insulatingcoating and means are provided to hold said winding in compressedrelation with adjacent turns separated by said insulating coating.
 5. Aninductive winding as set forth in claim 1 wherein cooling fins areprovided extending outwardly from said turns and formed as a singlepiece therewith.
 6. An inductive winding as set forth in claim 3 whereinsaid turns of said winding have cooling fins immediately part of saidturns and normal to said outer surface and longitudinal to said winding.7. A transformer comprising a wall having inner and outer surfacesforming a tubular-like member having a main longitudinal axis, a cutthrOugh said wall at a slight angle to a plane normal to the main axisto longitudinally space loops of said cut to form said wall into acontinuous winding of a plurality of turns, said turns being formed ofsuccessive members and corners connecting successive members at rightangles and at a slight angle to the plane of the preceding member toinductively form said turns, said members having uniform cross sectionsbetween respective corners and having successive flat side surfaces oneach side facing respective successive flat side surfaces of an adjacentturn, insulating means between said side surfaces, said side surfacesand said insulating means therebetween being compressed to transmit heattherethrough and said insulating means electrically isolate said turnsso as to solely pass current serially through said turns, an iron coreextending through said winding and a second winding electricallyisolated from said first winding and in inductive relation therewith forforming a transformer relation.
 8. A single piece of aluminum inductivedevice having a curved inductive winding with an insulating coatingcomprising, two terminals at the opposite ends of said winding andformed as a single piece therewith, inner and outer parallel membershaving substantially greater depth than longitudinal thickness, spacedpie-shaped members connecting the ends of said inner and outer members,connecting corners for joining successive members at right angles to oneanother, said connecting corners having transversely offset portionspositioning said successive members at a slight angle to one another toinductively form said members and corners into inductive turns, saidmembers having substantially planar side surfaces on opposite sides of arespective member in facing relation with planar side surfaces ofadjacent members with said insulating coating between respective facingsurfaces.
 9. An inductive winding as set forth in claim 1 wherein aferromagnetic core is provided extending through said winding.
 10. Aninductive winding as set forth in claim 1 wherein there is an extensionfrom one of said terminal portions for supporting current controlleddevices and dissipating heat.
 11. An inductive winding as set forth inclaim 10 wherein said extension has heat dissipating means extendingtherefrom.
 12. An inductive winding as set forth in claim 10 whereinsaid extension, said terminal portions and said turns are a singlepiece.
 13. An inductive winding as set forth in claim 1 wherein saidmembers have a substantially greater depth than longitudinal thickness.14. An inductive winding as set forth in claim 13 wherein heatconductive, electrical insulating means and means for pressing saidturns together are provided for transmission of heat between the sidesurfaces while said turns serially pass current.
 15. An inductivewinding as set forth in claim 1 wherein said terminal portions havenotches on the same side and at opposite ends of said winding and aclosed ferromagnetic core is provided extending axially through saidwinding.
 16. An inductive winding as set forth in claim 1 wherein saidturns have outer members and inner members of less thickness than saidouter members and have pie-shaped members on opposite sides of saidwinding for connecting opposite ends of said inner and outer members toform the winding in a curved shape.
 17. An inductive winding as setforth in claim 16 wherein a ferromagnetic core is provided extendingthrough said winding.
 18. An inductive winding as set forth in claim 16wherein insulating means and means for pressing said side surfacesfacing one another together is provided for transmission of heat betweensaid surfaces of said turns while serially passing current therethrough.19. An inductive winding as set forth in claim 1 wherein said turns havea heat conductive, electrically insulating means between said turns andmeans are provided for pressing said turns together with said sidesurfaces in facing relation passing heaT therebetween while passingcurrent serially therethrough and an extension is provided on one ofsaid terminal portions for carrying current devices controlling thecurrent through said winding, and said extension being in heat transferrelation with said device and said winding for dissipation of heat.